Mechanism for radio operated repeat motion



Jan. 2, 1934. c. B. MIRICK MECHANISM FOR RADIO OPERATED REPEAT MOTIONFiled Aug. 14, 1930 INVENTOR. Govt/e00 5. 91M

ATTORNEY UNITED STATES PATENT OFFICE MECHANISM FOR RADIO OPERATED REPEATMOTION Carlos B. Mirick, Washington, D. 0., assignor to NationalElectrical Supply Company, Washington, D. 0., a corporation of VirginiaMy invention relates broadly to remote control systems and moreparticularly to a circuit arrangement for a radio operated repeatmotion.

One of the objects of my invention is to provide a simplified circuitarrangement for accurately reproducing the movement of an indicatorremote from a distant control position by combining the effects of amultiplicity of signaling frequencies at a receiver according to a mullotiple modulated transmitter system.

Another object of my invention is to provide a circuit arrangement fortransmitting control signals of variable tone frequency and combiningthe effects of the variable tone frequencies selectively at a receiverfor reproducing the movement of a control mechanism at the distanttransmitter.

A further object of my invention is to provide a remote control systemfor reproducing mechanical movements at a distant station under controlof a master station in which only a single carrier frequency is requiredoccupyin a minimum width on the available frequency spectrum whileperforming a multiplicity of control functions by the effect of aselected modulated frequency or combination of modulating frequencies.

Other and further objects of my invention reside in a simplified systemfor accurately reproducing mechanical movements at a receiving stationunder control of a master mechanism at a distant transmitting station aswill be more fully pointed out in the specification hereinafterfollowing by reference to the accompanying drawing whichdiagrammatically shows the circuit arrangement of my invention.

Heretofore in the art it has been proposed to repeat the reading of thegyro compass on ship board on compass cards at different locations onthe ship. Such systems employ a multiplicity of line wire circuits andare relatively complicated. In utilizing a radio link in a system forproducing a repeat motion, individual circuits are not available and byreason of the congested condition of the ether and the wide demand forsignaling frequencies it is not practical to employ a wide band ofcarrier frequencies for control purposes. I have developed a mechanismfor radio operation of simplified construction by which a mechanicalmovementperformed at a master station may be accurately reproduced at adistant receiving station wherein the system operates on a singlecarrier frequency. I provide means for multiply modulating thetransmitter at different audio frequencies to effect a selectedoperation. At the 5 master station I provide a multiplicity ofpermanently established electromagnetic fields with predeterminedfrequency characteristics. The mechanism at the master station carriesan electromagnetic winding which is angularly movable in the permanentlyestablished electromagnetic field. When the mechanism of the masterstation is shifted to a selected position the winding iselectromagnetically coupled with a selected electromagnetic field orcombination of electromagnetic fields of different frequencies. Thetransmitter is therefore multiply modulated at a selected frequency orcombination of frequencies in accordance with the position of themechanism at the transmitter. At the distant receiver I provide meansfor receiving the transmitted signal- 7 ing energy and a multiplicity ofcircuits responsive to the different modulated notes of the transmitter.That is, separate frequency selection circuits are arranged at thereceiver in positions directly related to the angular positions of the 7means at a distant transmitter which create magnetic fields of differentfrequencies. A moving element disposed in the several magnetic fields atthe receiver selectively responds to the reproduced magnetic field of aparticular frequency or combination of magnetic fields de-' pending uponthe position of the control element at the distant transmitter. Only asingle carrier frequency is employed but any number of audio notes maybe employed for effecting the required control.

My invention may be applied to various types of repeat motions, oneexample of which is a compass system. A compass card at the transmittermay be attached to the angularly movable element for controlling thedistant receiver where a, similar compass card may be angularly shiftedto a position corresponding to the position of the compass card at thedistant transmitter.

Referring to the drawing in detail, reference I designates a rotatablearmature winding which is adapted to be angularly moved within amulti-'- plicity of electromagnetic fields of differing frequencycharacteristics. The electromagnetic fields have been designated asestablished by sets of radialy disposed electromagnetic windingsdesignated at 4, 5 and 6. The sets of windings, 4, 5 and 6 areindependently excited from suitable sources of different audio or tonefrequency such as generators operating at different audio frequenciesspaced one from another along the acoustic frequency spectrum, thegenerators being. indicated at A, B and C having leads '7, 8 and 9extending therefrom to the sets of field windings. That is fieldwindings 4 are energized from the alternator B through leads 8 at onefrequency., The field windings 5 are energized from alternator C throughleads 9 at a different frequency. The sets of windings 6 are energizedfrom alternator A through lead 7 at still a different frequency. Therotatable armature winding I is selectively magnetically coupled withany one of the several angularly disposed electromagnetic fields orcombinations thereof. In the position shown for example, the armaturewinding I is electromagnetically coupled both with the set of windings 4and the set-of windings 6. The armature winding I has the terminalsthereof connected to the collector rings 10 which lead to the primarywinding of modulation transformer 11. The transformer 11 has itssecondary winding connected in the modulation circuit of the transmitter12 which radiates signaling energy from antenna ground system 13-14modulated at different tone frequencies according to the coupling ofarmature winding I with the several electromagnetic fields. Thealtemators A, B and C are interconnected by shaft 2 driven by anysuitable prime mover which connects at 3 to driving shaft 2. Armaturewinding I is connected to the mechanical device from which a repeatmotion is to be transmitted such as the indicator 41 or a rotatablecompass card.

At the receiving station the antenna-ground system 15-16 connects to thereceiving apparatus 16a, the output circuit of which includes amultiplicity of frequency discriminating circuits. I have shown thesecircuits as including audio frequency transformers 23, 24 and 25, theprimary windings of each of which are shunted by the primary windings oftransformers 20, 21 and 22 forming closed circuits 17, 18 and 19. Tunedtrap circuits A, B and C are connected to the secondary windings oftransformers 20, 21 and 22 respectively and tuned to correspond to themodulating frequencies A, B and C at the transmitter. The tuned trapcircuit A includes tuning condenser 26 and variable resistance 27, eachof which may be adjusted to the characteristics of the modulatingfrequency A. The tuned trap circuit B includes tuning condenser 28 andvariable resistance 29 which are adjusted to tune the circuit to themodulating frequency of alternator B. Tuned trap circuit C is adjustedby means of tuning condenser 30 and variable resistance 31 to thefrequency of the modulating source 0 at the transmitter. The audiofrequency transformers 23, 24 and 25 connect to the input circuits ofelectron tube rectifiers 35, 36 and 37, respectively, the bias potentialfor each of which are adjusted by variable taps 32, 33 and 34. Theoutput circuit of each rectifier includes sets of radially positionedfield windings which I have designated at 38, 39 and 40. A rotatablearmature II is disposed within the field established by the several setsof field windings and the armature connected with an indicator 42 or acompass card similar to the indicator 41 or compass card at thetransmitter. Field windings 38 are connected in the output circuit ofrectifier 35. Field windings 39 are connected in the output circuit ofrectifier 36. The set of field windings 40 are connected in the outputcircuit of rectifier 37. The several sets of windings are energized toestablish an electromagnetic field if the associated rectifier circuitis excited and the associated rectifier circuit only responds to apredetermined frequency emitted by the transmitter. It will beunderstood that armature winding I picks up a modulation which dependsupon the position of winding 1. when directly in line with one of themagnets of a master system this will be a single frequency, and. whenmidway between two masters, it will be a double modulation, half of onefrequency and half of another. This modulationwhen transmitted to thereceiving end will be separated into its component frequencies betweentuned traps A, B, C in a manner proportional to the rotation of 1. Afterrectification, there results direct current in the magnet coilssurrounding armature II which follows this same relation. Therefore, thedriven rotor armature II when once oriented, will follow faithfuly themotions of the driving armature I. It will be noted that a single radiochannel is sufiicient for carrying this repeater motion and that theaction is continuous and not step by step which makes the repetitionextremely accurate. In order to make the repetition perfect, it isnecessary to adjust the sharpness of tuning of the three tuned outputsystems for proper relationwith the field distribution of the elementsin the driving transformer. This is done by varying the resistance 27,29 and 31 in the tuned trap circuits A, B, C'.

By the combined action of the electromagnetic field from the severalsets of electromagnets, the indicator 42 or associated compass card isshifted to a position corresponding to the position of the indicator orcompass card 41 at the transmitter. The frequency discriminatingcircuits .A', B and C screen the rectifiers in such manner that one ormore of the rectifiers are energized according to the particularfrequency or combination of frequencies at which the transmitter ismodulated. As heretofore explained this depends upon the angularposition of winding I with respect to the sets of electromagneticwindings at the transmitter.

While I have referred to the circuits as including an antenna-groundcircuit, it will be understood that any form of radio frequency emissionor reception circuit may be employed such as a doublet, a loop or otherform of collector or emitter.

While I have described my invention in" a certain preferred embodiment,I desire that it be understood that modifications may be made and thatno limitations upon my invention are intended other than are imposed bythe scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. A radio operated repeat motion system comprising a transmitteradapted to emit a predetermined carrier frequency for reception by adistant receiver, circuits'at said transmitter for variably modulatingsaid carrier frequency according to the position of a master mechanismat different audio frequencies and intermediate frequencies constitutedby combinations of the aforesaid frequencies, and circuits at saidreceiver adapted to respond to the frequency modulations of said carrierfrequency and a repeat motion mechanism controlled by said circuits forsimulating the position of said master mechanism at the transmitter.

2. In a radio operated repeat motion system, a transmitter adapted toemit a predetermined carrier frequency, a receiver adapted to receivethe carrier frequency thus transmitted, modulation means at saidtransmitter including a multiplicity of independent sources of audiofrequency energy each having. different frequency characteristics, amultiplicity of electromagnetic fields adapted to-be independentlyexcited from said source of audio frequency energy, an electromagneticwinding, a master mechanism for shifting said electromagnetic windingwithin said electromagnetic fields, a modulation circuit interconnectingsaid transmitter with said winding whereby the carrier frequency emittedby said transmitter is variably modulated according to the couplingbetween said winding with either an individual electromagnetic field orcombination of electromagnetic fields within which said winding isshifted, circuits at said receiver responsive to the modulatedfrequencies emitted by said transmitter, a repeat motion mechanism andmeans operated by said circuits for controlling said repeat motionmechanism for simulating the position of the master mechanism at thetransmitter.

3. In a radio operated repeat motion system, a transmitter adapted toemit a predetermined carrier frequency, a receiver adjusted to respondto the carrier frequency thus emitted, a modulation circuit connectedwith said transmitter, a multiplicity of sources of different audiofrequency at said transmitter, means connected with said sources forestablishing electromagnetic fields of corresponding frequencycharacteristics, a winding disposed in the said electromagnetic fieldsand connected with said modulation circuit, a master mechanism forcontrolling the movement of said winding within said electromagneticfields for establishing a coupling relationship with one or a pair ofsaid electromagnetic fields, a multiplicity of audio frequency selectioncircuits connected with said receiving circuit, a repeat motionmechanism and means operated by said frequency selection circuits foractuating said repeat motion mechanism and simulating the position ofsaid master mechanism at the transmitter.

4. In a radio operated repeat motion system, a transmitter adapted toemit a predetermined carrier frequency, a receiver adjusted to respondto the carrier frequency thus emitted, a modulation circuit connectedwith said transmitter, a multiplicity of sources of different audiofrequency at said transmitter, means connected with said sources forestablishing adiacent electromagnetic fields of corresponding frequencycharacteristics, a winding disposed in the said electromagnetic fieldsand connected with said modulation circuit, a master mechanism forcontrolling the movement of said winding through the adjacentelectromagnetic fields for modulating said transmitter at any one ofsaid audio frequencies when said winding is aligned with anelectromagnetic field of corresponding frequency or modulating-saidtransmitter at a different frequency when said winding is moved to aposition intermediate the aforesaid electromagnetic fields for utilizingthe combined effects thereof, a multiplicity of frequency selectioncircuits connected with said receiving circuit, a repeat motionmechanism, and a plurality of electromagnetic fields disposed radiallyabout said repeat motion mechanism and independently excited from saidfrequency selection circuits for effecting angular movement of saidrepeat motion mechanism and simulating the movement of said mastermechanism at the transmitter.

5. In a radio operated repeat motion system, a

transmitter adapted to emit a predetermined carrier frequency, areceiver adjusted to respond to the carrier frequency thus emitted,-amodulation plici'ty of sources of diiferent audio frequency atsaidtransmittenmeansconnectedwithsaidsources for establishing radiallyextendingelectromagnetic fields of corresponding frequencycharacteristics, a winding centrally disposed for rotative movement inthe said electromagnetic fields and connected with said modulationcircuit, a master mechanism for controlling the movement of said windingwithin said electromagnetic fields for establishing a couplingrelationship with one or a pair of said electromagnetic fields, amultiplicity of frequency selection circuits connected with saidreceiving circuit, a repeat motion mechanism, a multiplicity ofelectromagnetic fields radially disposed with respect to the axis ofradiation of said repeat motion mechanism, and

means for individually exciting each of said ra- 1 dially disposedelectromagnetic fields from each of said frequency selection circuits orcombination of adjacent electromagnetic fields for simulating themovement of the master mechanism at the transmitter.

6. In a radio operated repeat motion system, a transmitter adapted toemit a predetermined carrier frequency, a receiver adapted to respond tothe carrier frequency thus emitted, a modulation circuit at saidtransmitter, a master mechanism at said transmitter, means controlled bysaid master mechanism and connected with said modulation circuit forvariably modulating the carrier frequency emitted by said transmitteraccording to a multiplicity of differing audio frequencies and atfrequencies formed by a combination of the aforesaid audio frequencies,frequency selection circuits at said receiver each adapted to respond toone of the modulatin frequencies over said transmitter, a rotatablymounted repeat motion mechanism, a multiplicity of radially positionedelectromagnetic windings disposedon opposite sides of said repeatmechanism, and connections between the individual frequency selectioncircuits and selected electromagnetic windings for variably controllingthe movement of said repeat mechanism according to the position of themaster mechanism at said transmitter as determined by the operation ofeither of said audio frequencies or combination thereof.

7. In a radio operated repeat mechanism, a transmitter adapted to emit apredetermined carrier frequency, a receiver adapted to respond to thecarrier frequency thus emitted, a multiplicity of independent tonefrequency circuits connected to the output of said receive amultiplicity of electromagnetic field windings individually controlledby the operation of said tone frequency circuits, a repeat motionmechanism controlled by said electromagnetic fields, and means at saidtransmitter for variably modulating the carrier frequency according tothe movement of a master mechanism for correspondingly controlling theestablishment of either one or combination of electromagnetic fields forcorrespondingly coning the received energy 0! the frequencycorresponding to the said winding for producing a direct current changecorresponding to the irequency variation at the controlling station forangularly moving said member to a position corresponding to the positionof said rotatably mounted coil at the controlling station.

CARLOS B. MIRICK.

